Alginate-gelatin composite hydrogels for encapsulating Aloe vera extract; optimization, characterization, and release kinetics

Abstract

Composite alginate (ALG) hydrogels offer a promising solution to the rapid release challenges of encapsulated materials. This study developed ALG-gelatin (GE) hydrogels loaded with Aloe vera extract (AVE). A Resolution-V fractional factorial design and response surface methodology were employed to explore the impact of AVE and CaCl2 concentrations, hardening time, and the inclusion of GE as a wall material on the encapsulation efficiency (EE (%)) of the hydrogels. The optimal formulation identified was AVE at 4.41 %, CaCl2 concentration at 600 mM, and a hardening time of one hour, achieving the highest EE (%) of 93.16 %. Fourier transform infrared (FTIR) spectroscopy revealed chemical interactions between AVE and the ALG-GE capsules. Scanning electron microscopy of the ALG-GE hydrogel exhibited a rougher surface compared to calcium ALG hydrogels, characterized by the absence of surface cracks, reduced surface pores, and a meshed appearance, all contributing to the improved EE (%). The release rate of AVE from the hydrogels peaked at 70 °C and pH = 3, as indicated by an elevated release rate constant. These findings suggest that the ALG-GE hydrogel beads may serve as effective carriers for bioactive compounds, offering valuable insights for the formulation of enhanced delivery systems for these compounds in food applications.

Keywords

• Fractional factorial design
• Alginate-gelatin composite hydrogels
• Response surface methodology
• Release kinetic modeling